The present invention relates to a system for washing fabric in an automatic clothes washer and more particularly to a high performance system for washing fabrics in a horizontal axis washer that includes a fabric saturation step and a concentrated detergent solution washing operation.
Attempts have been made to provide an automatic clothes washer which provides comparable or superior wash results to present commercially available automatic washers, yet which uses less energy and water. For example, such devices and wash processes in a vertical axis machine are shown and described in U.S. Pat. Nos. 4,784,666 and 4,987,627, both assigned to the assignee of the present application, and incorporated herein by reference.
The basis of these systems stems from the optimization of the equation where wash performance is defined by a balance between the chemical (the detergent efficiency and water quality), thermal (energy to heat water), and mechanical (application of fluid flow through--fluid flow over--fluid impact--fabric flexing) energy inputs to the system. Any reduction in one or more energy forms requires an increase in one or more of the other energy inputs to produce comparable levels of wash performance.
Some prior art wash methods for horizontal axis washers, wash the fabric load in a concentrated detergent solution for the purpose of enhancing soil removal or reducing the amount of water consumed during the wash operation. For example, U.S. Pat. No. 4,489,455 discloses a horizontal axis washer which utilizes a reduced amount of wash fluid in a washing cycle in which the wash fluid is applied onto the fabric load and then the load is tumbled in the presence of the wash fluid for a given period of time. Recirculation of the wash liquid does not occur.
U.S. Pat. No. 3,197,980, assigned to the assignee of the present invention, discloses a horizontal washer and wash cycle in which the clothes load is subjected first to a deep fill to thoroughly wet all of the clothes, half the water is then removed from the washer and a normal detergent supply is introduced into the remaining wash bath. Thus, a "concentrated" detergent solution in the range of 0.40 to 0.50% by weight is applied to the clothes load during a tumbling agitation of the clothes. Recirculation of the wash fluid during this "concentrated" wash cycle is also disclosed. Following the "concentrated" portion of the wash cycle, the tub is refilled to a deep fill volume which dilutes the detergent concentration to the normal concentration of 0.20 to 0.25%. An additional tumble period at the normally recommended detergent concentration then occurs.
Significantly greater savings in water usage and energy usage than is achieved by heretofore disclosed wash systems and methods would be highly desirable.